Glossary
Term Description
GUI Graphical User Interface: The use of pictures rather than just words to
represent the input and output of a program. A program with a GUI runs
under a windowing system and has a screen interface capable of
displaying graphics in the form of icons, drop-down menus and a
movable pointer. The on-screen information is usually controlled /
manipulated by a mouse or keyboard.
HSSI High Speed Serial Interface: A differential ECL serial interface standard
developed by Cisco Systems and T3plus Networking primarily for use in
WAN router connections. It is capable of speeds up to 52 Mbit/s with
cables up to 50 feet in length. While HSSI uses 50-pin connector physically
similar to that used by SCSI-2, it requires a cable with an impedance of
11 Ω (as opposed to the 75 Ω of a SCSI-2 cable).
IEC International Electrotechnical Committee.
IF Intermediate Frequency: A frequency, commonly 70/140 MHz, to which a
carrier frequency is shifted as an intermediate step in transmission or
reception. The intermediate frequency is created by mixing the carrier
signal with a local oscillator signal, resulting in a signal at the difference
frequency.
IP Internet Protocol: The IP part of TCP/IP. IP implements the network layer
(layer 3) of the protocol, which contains a network address and is used
to route a message to a different network or sub-network. IP accepts
packets from the layer 4 transport protocol (TCP or UDP), adds its own
header to it and delivers a datagram to the layer 2 data link protocol. It
may also break the packet into fragments to support the Maximum
Transmission / Transfer Unit (MTU) of the network.
IRD Integrated Receiver Decoder: The Receiver with an internal MPEG
Decoder, which is connected to the subscriber’s TV. The IRD is
responsible for receiving and de-multiplexing all signals. The unit receives
the incoming signal and if CA is active, decodes the signal when
provided with a control word by the viewing card.
Domestic IRDs are also known as Set-Top Units or Set-Top Boxes.
ISDN Integrated Services Digital Network: The basic ISDN service is BRI (Basic
Rate Interface), which is made up of two 64 kbit/s B channels and one 16
kbit/s D channel (2B+D). If both channels are combined into one, called
bonding, the total data rate becomes 128 kbit/s and is four and a half
times the bandwidth of a V.34 modem
(28.8 kbit/s).
The ISDN high-speed service is PRI (Primary Rate Interface). It provides 23
B channels and one 64 kbit/s D channel (23B+D), which is equivalent to
the 24 channels of a T1 line. When several channels are bonded
together, high data rates can be achieved. For example, it is common
to bond six channels for quality videoconferencing at 384 kbit/s. In
Europe, PRI includes 30 B channels and one D channel, equivalent to an
E1 line.
ISO International Standards Organisation.
ITU-R International Telecommunications Union - Radiocommunications Study
Groups (was CCIR).
ITU-T International Telecommunications Union - Telecommunications
Standardisation Sector (was CCITT).
B-6 SBM75e Series Modulator Installation and Operation Manual
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